<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    </head>
    <body>
        <div onmouseover="mOver(this)" onmouseout="mOut(this)" style="background-color:green;width:120px;height:20px;padding:40px;color:#ffffff;">把鼠标移到上面</div>
        <script>
            function mOver(obj) {
                obj.innerHTML = "谢谢";
            }
            function mOut(obj) {
                obj.innerHTML = "把鼠标移到上面";
            }
        </script>
    </body>
</html>